KUALA LUMPUR—The technology being harnessed to find Malaysia Airlines Flight 370 includes advanced maritime-surveillance aircraft and naval crews scouring the horizon with binoculars. Indeed, anyone with an Internet connection can get involved as the search grinds on—still with no trace of the aircraft.

Malaysia continues to lead the vast operation, which grew to 26 nations on Monday and may ultimately cover an estimated 300,000 square miles. Malaysia began the complex process of dividing the search, calling on Indonesian...